Seems like it could be reproduced easily by a typical HN reader. “Fetch a site a thousand times and check the served JavaScript for weirdness” isn’t exactly a high bar. Defining weirdness is the secret sauce for sure, though!
Battery condition and orientation are useful for fingerprinting devices, alongside the more commonly-known canvas attacks.
Your battery status may be used to track you online, 98 comments (2016) https://news.ycombinator.com/item?id=12208880